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Diet drinks containing aspartame : An in vitro cause of false positive tests for phenylketonuria
PEDIATRIC LABORATORY MEDICINE CONGRESS During routine neonatal screening for Phenylketonuria by thin layer chromatography five high phenylalanine results ( 200-500 urnol/I : normal< 240 ) were found in one week. All the blood spot samples had been collected onto filter paper cards by ONE midwife. The identity of phenylalanine was eontirmed by ion exchange chromatography. All five babies had repeat plasma samples taken and the phenylalanine levels were normal. No contamination was obvious but, when examined under a uv lamp, a contaminated area was visible on four of the five blood spot cards. It was postulated that this could be a diet drink containing Aspartame ( N - aspartylphenylalani.ne methyl ester ) A normal fresh blood was spotted onto a blood spot card that had previously been soaked in a diet drink and allowed to dry. We demonstrated a high phenylalanine level in the extracted blood spot. Plasma from the same blood did not convert the diet drink to phenylalanine. It is postulated that a red cell dipeptidase is responsible for this action. It is likely in this case that the contamination occurred before distribution of the blood spot cards to the midwife concerned in this unfortunate incident. Conclusion: it is recommended that manufacturers of neonatal screening cards should package the cards in waterproof containers.
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NIRS (infraAlyzer 500, Technicon) was used to evaluate fecal conjugated bilirubin and fat for screening for biliary atreaia. NIRS is useful for screening and diagnosis of hiliary atresia but is not available clinically because it is large and expensive. The Minolta Jaundice Meter (TcB), however, is compact, easy to operate and available for clinical use. TcB is well known for its usefulness in evaluating the degree of skin yellowness. The samples used were manually homogenized feces collected from infants. Fecal samples were measured concurrently by NIKS and TcB. Reflected light from the surface of the feces was measured automatically at 4 nm intervals from 600 nm to 2500 nm wavelength by NIPS. Absorbance in second derivative spectra at 730 nm was significantly different in healthy infants compared to cholestatic infants. The fecal TcB index from infants with cholestasis (N=5) was significantly lower than that of healthy infants (N=100), 10.3±2.7 (n=30) vs 32.0-~-6.0 (n=100), p<0.001. There was also significant correlation between the fecal TcB index and fecal conjugated bilimbin obtained by NIRS (r--0.52, p<0.01~ n=130). The fecal TcB index increased significantly in intrahepatic cholestasis, but remained unchanged in biliary atresia during the clinical course. Our study shows that TcB can objectively evaluate fecal yellowneas and be clinically applicable and useful in screening for biliary atresia.
8 Detection of liver cly~unction in the newborn: a~ screening approach
Keffler S, Kely DA', Green A Department of CEnical Chemistry and "The Liver Unit, The Children's Hospital, Birmingham, UK Extra-hepatic biliary atresia and some other causes of neonatal liver disease carry a high mortality and morbidity, especially if not treated eady in life. Delayed referral of infants with prolonged jaundice continues to be a significant problem despite an increase in publicity fur parents and health professionals, notably by the Children's Liver Disease Foundation's Yellow Alert Campaign. One approach to reduce the age of referral and diagnosis is population screening to detect significant conjugated hyperbilirubinaemia as an index of liver dysfunction. To investigate this possibility, and to provide reference data on bilirubin and its conjugated and unconjugated fractions in a normal newborn population, we have anonymously tested 1200 babies aged 6-28 days. We analysed surplus plasma from routine screening specimens by dry slide technology using a Kodak Ektschom analyear. Total bilirubin concentration ranged from 9 to 428umol/I and unconjugated bilirubin from 1 to 373umol/I. Both total and unconjugated fractions were > 200umol/I in approximately 10% of cases, presumably mainly due to physiological jaundice. However, although the conjugated bilirubin concentration range was 0175umol/! it was only > 40umol/I la provisional cut-off suggested by earlier work), in 5 babies 10.4%}. Using a cut-off of conjugated bilirubin >20% that of total bilirubin, a figure frequently quoted in the literature, 23 babies (2.0%} had results above this limit. It is likely that an increased conjugated bilirubin concentration is a more specific marker of liver dysfunction and in babies with a result above 40umol/I further investigation would be indicated. This approach has the potential to provide newbom screening for detecting liver dysfunction and hence m improve the ago of referral and the prognosis of neonatal liver disease.
MECHANISTIC ASPECTS INVOLVED IN HYPERLIPIDEMIA OCCURING IN GLYCOGEN STORAGE DISEASE TYPE I (GSD-I) PATIENTS. E. Delvin1, P. Julian2, E.Seidman I and E. Levy I, Research Center, SteoJnstine Hospital and University of Montreal, Montreal t and Lipids Diseases Research Center, Centre hospitalier de l'universit6 Laval, Quebec2, Canada Hyperlipidemia is one of the more severe pathophysiological manifestations of GSD4. In this study, we determined plasma lipids to assess lipoprotein disorders in 10 young patients (8-17 yrs). We also explored possible mechanisms responsible for the striking hypertriglyceridemia (HTG). Plasma triglyceride (TG) levels were markedly elevated and reached 20- to 60- fold normal values (18.6 + 5.2 vs 0.75 + 0.04 mmol/L p<0.001). The patients also showed significantly higher levels of LDL-Cholesterol (5.8 + 0.9 vs 2.8 + 0.2 mmol/L p<0.001) and lower HDLCholesterol (0.56 + 0.10 vs 1.30 -F 0.10 mmol/L p<0.001). HTG was ass~iated with both increased production and decreased catabolism of TG-rich lipoproteins. In addition to the enhanced TG production, decreased circulating lipoprotein lipaso (LPL) activity was noted in GSD-I patients (0.98 + 0.24 vs 4.80 + 0.90 #moles FFa ml-~hr"~ p<0.01). Interestingly plasma levels of apolipoprotein C-H, the activator of LPL, were decreased. At the time of wansplantation, using labeled substrates, we also demonstrated increased TG synthesis in one patient's liver. Several factors were implicated in the LPL deficiency: diminished LPL protein synthesis, altered quality of lipoproteins and increased hepatic LPL clearance. Therefore, our data show that the hyperlipidemia observed in GSD-I patients is due to multiple mechanisms.
7 Use of Near Infrared Spectroscopy (NIRS) for Screening of Biliary Atresia: Compared with Minolta Jaundice Meter
Yoshitada Yamauchi,Takashi Akiyama,Koji Aoyama. Department of Pediatrics and Pediatric Surgery, Children's Medical Center, Okayama National Hospital, 700 Japan 358
Blood Lipids and Energy Expenditure in Primary School Children. J Anne Payne 1, Andrew C Payne2, and Neville R Belton I. tDepartment of Child Life and Health, University of Edinburgh, Edinburgh, EH9 1UW and 2Department of Physiotherapy, Queen Margaret College, Edinburgh EH6 8HF, Scotland, UK CLINICAL BIOCHEMISTRY, VOLUME 28, J U N E 1995
6
NIRS (infraAlyzer 500, Technicon) was used to evaluate fecal conjugated bilirubin and fat for screening for biliary atreaia. NIRS is useful for screening and diagnosis of hiliary atresia but is not available clinically because it is large and expensive. The Minolta Jaundice Meter (TcB), however, is compact, easy to operate and available for clinical use. TcB is well known for its usefulness in evaluating the degree of skin yellowness. The samples used were manually homogenized feces collected from infants. Fecal samples were measured concurrently by NIKS and TcB. Reflected light from the surface of the feces was measured automatically at 4 nm intervals from 600 nm to 2500 nm wavelength by NIPS. Absorbance in second derivative spectra at 730 nm was significantly different in healthy infants compared to cholestatic infants. The fecal TcB index from infants with cholestasis (N=5) was significantly lower than that of healthy infants (N=100), 10.3±2.7 (n=30) vs 32.0-~-6.0 (n=100), p<0.001. There was also significant correlation between the fecal TcB index and fecal conjugated bilimbin obtained by NIRS (r--0.52, p<0.01~ n=130). The fecal TcB index increased significantly in intrahepatic cholestasis, but remained unchanged in biliary atresia during the clinical course. Our study shows that TcB can objectively evaluate fecal yellowneas and be clinically applicable and useful in screening for biliary atresia.
8 Detection of liver cly~unction in the newborn: a~ screening approach
Keffler S, Kely DA', Green A Department of CEnical Chemistry and "The Liver Unit, The Children's Hospital, Birmingham, UK Extra-hepatic biliary atresia and some other causes of neonatal liver disease carry a high mortality and morbidity, especially if not treated eady in life. Delayed referral of infants with prolonged jaundice continues to be a significant problem despite an increase in publicity fur parents and health professionals, notably by the Children's Liver Disease Foundation's Yellow Alert Campaign. One approach to reduce the age of referral and diagnosis is population screening to detect significant conjugated hyperbilirubinaemia as an index of liver dysfunction. To investigate this possibility, and to provide reference data on bilirubin and its conjugated and unconjugated fractions in a normal newborn population, we have anonymously tested 1200 babies aged 6-28 days. We analysed surplus plasma from routine screening specimens by dry slide technology using a Kodak Ektschom analyear. Total bilirubin concentration ranged from 9 to 428umol/I and unconjugated bilirubin from 1 to 373umol/I. Both total and unconjugated fractions were > 200umol/I in approximately 10% of cases, presumably mainly due to physiological jaundice. However, although the conjugated bilirubin concentration range was 0175umol/! it was only > 40umol/I la provisional cut-off suggested by earlier work), in 5 babies 10.4%}. Using a cut-off of conjugated bilirubin >20% that of total bilirubin, a figure frequently quoted in the literature, 23 babies (2.0%} had results above this limit. It is likely that an increased conjugated bilirubin concentration is a more specific marker of liver dysfunction and in babies with a result above 40umol/I further investigation would be indicated. This approach has the potential to provide newbom screening for detecting liver dysfunction and hence m improve the ago of referral and the prognosis of neonatal liver disease.
MECHANISTIC ASPECTS INVOLVED IN HYPERLIPIDEMIA OCCURING IN GLYCOGEN STORAGE DISEASE TYPE I (GSD-I) PATIENTS. E. Delvin1, P. Julian2, E.Seidman I and E. Levy I, Research Center, SteoJnstine Hospital and University of Montreal, Montreal t and Lipids Diseases Research Center, Centre hospitalier de l'universit6 Laval, Quebec2, Canada Hyperlipidemia is one of the more severe pathophysiological manifestations of GSD4. In this study, we determined plasma lipids to assess lipoprotein disorders in 10 young patients (8-17 yrs). We also explored possible mechanisms responsible for the striking hypertriglyceridemia (HTG). Plasma triglyceride (TG) levels were markedly elevated and reached 20- to 60- fold normal values (18.6 + 5.2 vs 0.75 + 0.04 mmol/L p<0.001). The patients also showed significantly higher levels of LDL-Cholesterol (5.8 + 0.9 vs 2.8 + 0.2 mmol/L p<0.001) and lower HDLCholesterol (0.56 + 0.10 vs 1.30 -F 0.10 mmol/L p<0.001). HTG was ass~iated with both increased production and decreased catabolism of TG-rich lipoproteins. In addition to the enhanced TG production, decreased circulating lipoprotein lipaso (LPL) activity was noted in GSD-I patients (0.98 + 0.24 vs 4.80 + 0.90 #moles FFa ml-~hr"~ p<0.01). Interestingly plasma levels of apolipoprotein C-H, the activator of LPL, were decreased. At the time of wansplantation, using labeled substrates, we also demonstrated increased TG synthesis in one patient's liver. Several factors were implicated in the LPL deficiency: diminished LPL protein synthesis, altered quality of lipoproteins and increased hepatic LPL clearance. Therefore, our data show that the hyperlipidemia observed in GSD-I patients is due to multiple mechanisms.
7 Use of Near Infrared Spectroscopy (NIRS) for Screening of Biliary Atresia: Compared with Minolta Jaundice Meter
Yoshitada Yamauchi,Takashi Akiyama,Koji Aoyama. Department of Pediatrics and Pediatric Surgery, Children's Medical Center, Okayama National Hospital, 700 Japan 358
Blood Lipids and Energy Expenditure in Primary School Children. J Anne Payne 1, Andrew C Payne2, and Neville R Belton I. tDepartment of Child Life and Health, University of Edinburgh, Edinburgh, EH9 1UW and 2Department of Physiotherapy, Queen Margaret College, Edinburgh EH6 8HF, Scotland, UK CLINICAL BIOCHEMISTRY, VOLUME 28, J U N E 1995